Concept of the Soft and hard magnetic materials

Soft magnetic materials:

Soft magnetic materials have steeply rising magnetization curve, high permeability, high saturation value, a small area of the hysteresis loop. It is easy to orient the domains so these can be easily magnetized however these can lose their magnetism easily too. Soft iron, silicon steel are examples of soft magnetic materials.

Use of soft magnetic materials:

1)Pure iron

2)Carbon Steel

3)Cast iron

4)Iron-silicon alloys

Pure iron:

It is also known as the ingot iron. It is ferrous material with extra low carbon content less than 0.1%. It has low resistivity so it results in a large eddy current loss when the material is used on alternating flux. Therefore this material is used for steady flux. It is used as a core for electromagnets, core for electromagnets etc.

Electrolytic ion is the example of the pure ion. It is produced by electrolysis. It has low magnetic properties as it is highly saturated with hydrogen.

Carbon steel:

It contains 0.05 to 0.3% carbon.Magnetic properties are similar to pure iron. These are also used to carry steady flux. Increasing the carbon content increases the mechanical strength but on other hand decreases the permeability. Hence it is used in machines where the strength is prime important.

Cast iron:

It is also iron with carbon content varying from 1 to 4.5%. Its magnetic characteristics are inferior to pure iron. It is used for making the body of the large d.c machines. It is used to complete the magnetic path in electrical appliances. It is used in relay and telephone.

Iron-silicon alloys:

To improve the magnetic properties of pure iron some other element is added in low and definite proportion. One is silicon and its proportion varies from 0.5% to 5% by weight this alloy is known as silicon steel.

Hard magnetic materials:

These materials have gradually rising magnetization curve and have a large area of the hysteresis loop. It is difficult to orient the domains so these are difficult to magnetize. These can store sufficient energy and retain for a long time so these are used for making permanent magnets.

Used of the hard magnetic materials:

Hard magnetic materials are classified on basis of their manufacturing process these are:

1)Cast alloys

2)Powder alloys

3)chromium steel

4)cobalt steel

5)cunife

Cast alloys:

It is brittle

it is hard

it has low magnetic properties

some other materials are added to improve properties

Powder alloys:

it has good retentivity

it has sufficient coercive force

chromium steel:

It is hard and can not break very easily

It is used to make permanent magnets

is is used to make magnetic poles in the dynamo.

cobalt steel:

It can be machined after annealing

Its coercive force is 104 AT/m

saturation flux density is 2.5 Wb/m2

It is very hard and strong metal

It is used in heavy duty machines, fans, and motors.

cunife:

It comprises 60% copper,20% nickel and 20% iron.

It is ductile and malleable so wires can be drawn and thin sheets can be made.